Message-Id: <s5f90ede.048@YCC.COM>
Date: Fri, 11 Sep 1998 11:51:28 -0500
From: "Bill Gradwohl" <Bill@YCC.COM>
To: lancair.list@olsusa.com
Subject: Re: Coax cable selection
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One of the things to consider with coax is how will you terminate the ends.
The choice of termination method also determines the type of coax to get
to begin with.

We've installed thousands of coax network connections over the years as 
networking consultants, and the best method of termination is either a 
soldered or crimped on connector. By best, I mean reliable, low noise, and 
likely to last a long time.

Almost no one is willing to solder on a connector however. 

That leaves the crimped on variety as the best option. The screw on types
are terrible. They corrode over time, and we've seen serious networking 
problems due to the connectors. Their physical properties are also not very
good. The connectors are easily pulled off the cable with minimal effort. 
We've also seen that many people damage the coax in the process of 
trying to put on the screw on connectors.

The crimp on connectors effectively squeeze the connector onto the coax.
This means that the coax had better offer enough physical resistance to
get a good crimp. Some coax cables have a hollow plastic core with a 
plastic spiral keeping the center conductor centered within the coax. The
hollow part is easily compressed by the crimp process, and therefore does
not produce a quality end product. The coax may be electrically good, the
connector may be good, but the combination doesn't work very well.

Other types of coax have a relatively soft foam core that surrounds the 
center conductor. This is better, but still not what you want. The best
coax has a hard plastic core that is difficult to deform. When a crimp tool
wraps a connector on that type of coax, it's there to stay. We've tried to
rip the connectors off these cables and usually can't do it.

We have also found that plenum rated coax is physically tougher and 
just slightly smaller in diameter than regular PVC jacketed coax. Coax
with a plenum rating is usually Teflon coated, and will not give off poison
gas if it burns.

One last point. If you can see a deformation in the coax where it was
kinked during the installation process, consider it a bad cable and 
replace it. Coax should be installed so as to produce bends with a 
minimum bend radius of 6 inches. If you kink the cable as is likely to
happen if it is unspooled improperly, it will radiate your signal at the kink
and less at your antenna.

Bill Gradwohl
IV-P N858B